[R] Extract elements from objects in a list

[Jeremy Miles]

Excellent, thanks.

On 28 June 2011 16:36, jim holtman <jholtman at gmail.com> wrote:
> forgot to sent the sapply solution:
>
>> sapply(x, '[', 3)
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.4769 0.4880 0.4916 0.4021 0.4474 0.4449 0.5169 0.5067 0.5189 0.4088
> 0.4887 0.5392 0.4964 0.4141 0.5155 0.4461
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.4918 0.4910 0.5432 0.4784 0.5482 0.6263 0.5420 0.4933 0.5534 0.5066
> 0.5900 0.4553 0.4859 0.5721 0.5442 0.5105
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.4580 0.5268 0.4833 0.5178 0.5210 0.5808 0.4720 0.5457 0.5910 0.5796
> 0.5329 0.5178 0.4674 0.4280 0.4061 0.5665
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.4963 0.5013 0.4791 0.5329 0.4770 0.5926 0.4709 0.6042 0.5020 0.4788
> 0.5261 0.5010 0.4394 0.5339 0.5655 0.5200
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.5586 0.5362 0.5719 0.4851 0.4831 0.5458 0.5331 0.5611 0.4336 0.4727
> 0.5497 0.4768 0.5305 0.5261 0.5667 0.5107
> Median Median Median Median Median Median Median Median Median Median
> Median Median Median Median Median Median
> 0.5209 0.5635 0.4789 0.5428 0.5372 0.5403 0.5086 0.5470 0.4219 0.4758
> 0.4824 0.5165 0.5035 0.4833 0.4754 0.5227
> Median Median Median Median
> 0.6169 0.4904 0.4773 0.4779
>
> On Tue, Jun 28, 2011 at 7:22 PM, Jeremy Miles <jeremy.miles at gmail.com> wrote:
>> Hi All,
>>
>> I want to extract elements of elements in a list.
>>
>> Here's an example of what I mean:
>>
>> If I create a list:
>>
>> x <- as.list(100)
>> for(loop in c(1:100)) {
>>        x[[loop]] <- summary(runif(100))
>>        }
>>
>>
>>> head(x)
>> [[1]]
>>   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
>> 0.02271 0.25260 0.58130 0.52120 0.77270 0.99670
>>
>> [[2]]
>>    Min.  1st Qu.   Median     Mean  3rd Qu.     Max.
>> 0.006796 0.259700 0.528100 0.515500 0.781900 0.993100
>>
>> [[3]]
>>   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
>> 0.00927 0.22800 0.40780 0.46410 0.69460 0.98780
>>
>> I want to extract (say) the medians as a vector.  This would be:
>> x[[1]][[3]]
>> x[[2]][[3]]
>> x[[3]][[3]]
>>
>> I thought there would be a way of doing this with something like
>> apply(), but I cannot work it out.  Is there a way of doing this
>> without a loop?  Thanks,
>>
>> Jeremy
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Jim Holtman
> Data Munger Guru
>
> What is the problem that you are trying to solve?
>